1. Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a method for producing an electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus.
2. Description of the Related Art
An electrophotographic photosensitive member repeatedly used in an electrophotographic apparatus desirably has high wear resistance.
Japanese Patent Laid-Open No. 2000-066425 describes a technique of improving the wear resistance of an electrophotographic photosensitive member. According to this technique, a polymerized product obtained through polymerization of a charge transporting compound having a chain polymerizable functional group is added to a surface layer of the electrophotographic photosensitive member. Japanese Patent Laid-Open No. 2000-066425 teaches that an acryloyloxy group and a methacryloyloxy group are particularly favored as the chain polymerizable functional group.
As the wear resistance of the electrophotographic photosensitive member is improved, it becomes more difficult to refresh the surface of the electrophotographic photosensitive member and the material that has undergone chemical changes by repetitive use tends to remain on the surface of the electrophotographic photosensitive member. Discharge products generated through a charging process that involves discharging are thought to be the main cause of the chemical changes of the materials constituting the surface of the electrophotographic photosensitive member. In particular, ozone, which is one of the discharge products, accelerates oxidation reactions of materials constituting the surface of the electrophotographic photosensitive member and the increase in the number of polar groups on the surface of the electrophotographic photosensitive member results.
The increase in the number of polar groups on the surface of the electrophotographic photosensitive member causes that portion to readily act as a toner absorbing point and the decrease in toner transfer efficiency from the electrophotographic photosensitive member to a transfer material such as a paper sheet or an intermediate transfer material occurs in some cases.